Pure elemental iron, Fe, is generally produced by carbothermic reduction reactions of medium- or high-grade iron ore. The processes involve carbon-based coke (i.e., processed from coal), and generally involve multiple steps such as cokemaking, palletization, and sintering. Additionally, the multi-stepped processes produce carbon-based emissions throughout each step. The carbon acts as a reducing agent and reacts with iron ores to produce elemental iron. By using hydrogen as a reducing agent, however, the process reduces carbon-based emissions and is generally simpler.
As one example, the application of hydrogen in a plasma arc, e.g., a hydrogen plasma smelting reduction, intensifies the reduction processes. Hydrogen-based processes enable production of iron in a one-stage process and avoid introducing carbon into the atmosphere.
One traditional process for reducing iron ore is the production of liquid iron via blasts furnaces and/or basic oxygen furnaces. This is the longest and most time-consuming reduction method. Blast furnace production of liquid iron is a four-step process. This process generally has the highest CO2 emissions, but it is optimized for energy efficiency.
Another reduction process combines direct reduction with electric arc furnaces. This is a three-step process that reduces the use of carbon-based reduction. However, it is not a process optimized for energy efficiency.
A third process, hydrogen plasma smelting reduction, is a one-step process focusing on reducing conditions. Hydrogen plasma smelting reduction applies high plasma temperatures to hydrogen gas mixtures to intensify the reduction processes. Because the enthalpies of molecular hydrogen and liquid iron oxide are approximately equal, a high plasma temperature (15,000-20,000° C.) is generally required to facilitate the reduction process.
Nevertheless, for all the processes described above, there are significant thermodynamic energy trade-offs leading to increased production costs and/or increased carbon-based emissions. Additionally, each process has underutilized resources like heat gradients (i.e., from blast furnaces) and electrical fields (i.e. from electric arc furnaces) which both require separate production of energy to create. Accordingly, aspects consistent with the disclosed embodiments address these concerns by providing methods of reducing metal oxides in a plasma arc torch in a way that optimizes resources.
Moreover, while iron reduction processes solutions exist, none are as efficient as the means described herein. The present disclosure provides systems and methods for using reduction processes to better harness excess heat gradients and electric fields in hydrogen plasma smelting reduction.